<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var m=parseInt(prompt("请输入第一个数字"));
        var t=prompt("请输入运算符号(+ - * /)");
        var n=parseInt(prompt("请输入第二个数字"));
        function fn(a,b,c){
            var sum=0;
            switch(b){
                case "+":
                    sum=a + c;
                    break;
                case "-":
                    sum=a - c;
                    break;
                case "*":
                    sum=a * c;
                    break;
                case "/":
                    sum=a / c;
                    break;
            }
            return sum;
        }
        console.log(fn(m,t,n));
    </script>
</body>
</html>